EKG Flashcards
What is the charge of the resting cardiac cell?
negative
What ions can be found inside and outside the resting cardiac cell?
Potassium - inside
Sodium - outside
What term describes when a cardiac cell becomes positively charged?
Depolarization
By what process are cardiac cells returned to a negative state?
Sodium-potassium pump, an active transport system
On an ekg, what represents atrial depolarization?
P wave
On an ekg, what represents ventricular depolarization?
QRS complex
On an ekg what represents ventricular repolariazation?
T wave
What is the flat line between the P wave and QRS complex?
PR interval
What is the flat line between the QRS complex and T wave?
ST Segment
List the pathway of the conduction system?
Sinus node > Interatrial tracts > atrium > internodal tracts > AV node > bundle of His > bundle branches > Purkinje fivers > Ventricles
Where is the SA node located?
upper right atrium just beneath the opening of the superior vena cava
List four characteristics of cardiac cells
Automaticity
Conductivity
Excitability
Contractility
What is the inherent rate of the sinus node?
60-100 beats per minute
What is the inherent rate of the AV junction?
40-60 beats per minute
What is the inherent rate of the Ventricle?
20-40 beats per minute
What leads can be seen in the first column of a 12 lead EKG?
Leads I, II, III
What leads can be seen in the second column of a 12 lead EKG?
aVR, aVL, aVF
What leads can be seen in the third column of a 12 lead EKG?
V1, V2, V3
What leads can be seen in the fourth column of a 12 lead ekg?
V4, V5, V6
What is the normal PR interval?
0.12 to 0.20 seconds
How is the PR interval measured?
From the beginning of the P wave to the beginning of the QRS
What should the P wave measure?
no more than 0.10 seconds
What is the normal QRS interval?
0.12 seconds
How much time does a single small block on ekg paper represent?
0.4 seconds
What term describes when a cardiac cell cannot respond to another impulse no matter how strong?
Absolute refractory period
How much time does a big block on ekg paper represent?
.20 seconds
how many big blocks on ekg paper represent a second?
5
On what plane do limb leads read the heat’s current?
frontal (top to bottom/right to left)
What plane do the precordial leads read the heart’s current?
horizontal plane
What are the augmented leads?
aVR
aVL
aVF
Which limb leads should have positive QRS complexes?
I, II, III, aVL and aVF
Which limb leads should have negative QRS complexes?
aVR
Which precordial leads should have negative QRS complexes?
V1 and V2
Which precordial leads should have positive QRS complexes?
V5 and V6
Wich precordial leads should be isoelectric?
V3 and V4
What does aV stand for?
Augmented voltage
What is the five steps to rhythm interpretation?
1) Are there QRS complexes and are they the same shape?
2) What’s the regularity?
3) Whats the heart rate?
4) Are there P waves? are they the same shape? in the same place relative to QRS?
5) PR and QRS interval
Normal sinus rhythm characteristics:
QRS narrow, uniform shape
Regular
Heart rate 60-100
Upright uniform shape P waves married to the QRS
PR 0.12-0.20 sec, constant QRS <0.12 secs
What can deviation of the QRS axis indicate?
chamber enlargement, MI, and origin of some arrhythmia
Which two leads are examined to use the quadrant approach to determine the axis?
Lead I
aVF
When using the quadrant approach to determine axis, what would you expect to see with a normal axis?
Positive QRS in Lead I and aVF
When using the quadrant approach to determine axis, what would you expect to see in a right axis deviation?
Negative Lead I
Positive aVF
When using the quadrant approach to determine axis, what would you expect to see in a left axis deviation?
Positive Lead I
Negative aVF
